We studied mechanisms by which extreme oxygen concentrations affect metabolism of collagen and fibroblasts. We developed models such as long-term exposure of rats to low (9 percent) and high (80 percent) oxygen; incubation of Ascaris lumbricoides under N2 or 70 percent O2; collagen synthesis in animal species (Mollusca) adapted to a molecular oxygen-free environment; and various cell lines of fibrogenic and epithelial cells at various pO2. We evaluated the effect by biological, biochemical, and ultrastructural methods. Our experiments indicate that mechanisms of enhanced collagen accumulation in low- and high-oxygen environments consist of changes in the type of metabolism with either a) accumulation of lactate which stimulates prolyl hydroxylase, or b) labilization of biomembranes by enhancing lipid peroxidation-related tissue injury followed by secondary organization of the lesion by fibroproliferative inflammation. Experiments indicate that fibrogenic and epithelial cells differ in several biochemical parameters in their reactivity to low oxygen, the kidney cells quickly requiring a change in their energy metabolism (formation of LDH-5). A combination of all aspects of the research mentioned above is proposed for the following year.